deep copy domain.Config object before returning it

hack/update-codegen.sh

@@ -32,7 +32,7 @@ ${CODEGEN_PKG}/generate-groups.sh "deepcopy,client,informer,lister" \
 
 # Depends on generate-groups.sh to install bin/deepcopy-gen
 ${GOPATH}/bin/deepcopy-gen --input-dirs \
-  github.com/knative/serving/pkg/controller/revision/config,github.com/knative/serving/pkg/autoscaler,github.com/knative/serving/pkg/logging \
+  github.com/knative/serving/pkg/controller/revision/config,github.com/knative/serving/pkg/controller/route/config,github.com/knative/serving/pkg/autoscaler,github.com/knative/serving/pkg/logging \
   -O zz_generated.deepcopy \
   --go-header-file ${SERVING_ROOT}/hack/boilerplate/boilerplate.go.txt
 

pkg/controller/route/config/doc.go

@@ -14,6 +14,8 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
+// +k8s:deepcopy-gen=package
+
 // Package config holds the typed objects that define the schemas for
 // assorted ConfigMap objects on which the Route controller depends.
 package config

pkg/controller/route/route.go

@@ -259,7 +259,7 @@ func loggerWithRouteInfo(logger *zap.SugaredLogger, ns string, name string) *zap
 func (c *Controller) getDomainConfig() *config.Domain {
 	c.domainConfigMutex.Lock()
 	defer c.domainConfigMutex.Unlock()
-	return c.domainConfig
+	return c.domainConfig.DeepCopy()
 }
 
 func (c *Controller) routeDomain(route *v1alpha1.Route) string {